Fusobacterium necrophorum, a gram negative and rod-shaped anaerobe, is the primary etiologic agent of liver abscesses in ruminant animals, including cattle and sheep. F. necrophorum strains are divided into two subspecies, subsp. necrophorum (FNN) and subsp. funduliforme (FNF). In addition to liver abscesses, the organism is also the primary etiologic agent of foot rot, foot abscesses, calf diphtheria, and is frequently isolated from cases of mastitis, metritis, and necrotic lesions of the oral cavity. It has also been recognized as a human pathogen since the late 1800s. Antibiotics have been used in animal agriculture to treat and prevent fusobacterial infections.
The increasing concern over the use of antibiotics in food animals and its impact on rise of multidrug resistant bacteria has already led to the ban of certain antibiotics in animals. The sub-therapeutic use (i.e., use in the absence of disease) for growth promotion is a practice that is becoming increasingly controversial, since it is implicated as increasing antibiotic resistance among pathogenic bacteria of animals and humans. Additionally, there is a growing demand for natural and organic beef (requirements include cattle be raised without use of antibiotics in feed), which warrants effective vaccines as a method to prevent infections. Accordingly, there is a need to develop an effective vaccine for the prevention of fusobacterial infections, particularly liver abscesses and foot rot.
U.S. Pat. Nos. 5,455,034, 5,492,694, and 5,861,162 describe leukotoxoid vaccines that immunize cattle and sheep against leukotoxin, an important virulence factor, released by F. necrophorum after it gains access into the ruminal wall and the liver. While this vaccine reduces the severity and incidence of the disease (by up to 40%) it does not eliminate its occurrence. Moreover, leukotoxoid and bacterin vaccines frequently contain lipopolysaccharides and other cellular derivatives that have side effects (fever, injection site abscesses, etc) and may impact feed-intake and weight gain.
Accordingly, a need still exists for effective prevention and treatment of fusobacterial infections. The present invention provides compositions and methods for effective prevention and treatment of fusobacterial infections.